Overview
Backup jobs for NAS shares have been failing to include symbolic link (symlink) files, marking them as “missed files” with the error message:
“The parameter is incorrect.”
This occurs when NAS shares backed by Amazon FSx for Windows File Server over SMB are used.
Problem Description
Symlink files in the NAS share are flagged as missed during backup due to the agent being unable to recognize them, resulting in the specified parameter error.
Observations
Only symlink files failed; other files backed up successfully.
Test symlinks created within the same share also failed.
File attributes showed as “Normal (N)” instead of “Archive + Link (AL)”. PowerShell indicated no link type, and Windows Explorer displayed the files without the .smlink extension.
These indicators confirmed the backup agent and the file system were treating symlinks as regular files.
Cause
Amazon FSx for Windows File Server does not support symbolic links when accessed via SMB. AWS DataSync documentation notes:
Because FSx over SMB doesn’t expose symlinks properly, and when the backup agent tries to read these files it throws the “parameter is incorrect” error.
Resolution
Switch the NAS share protocol from SMB to NFS, where symbolic links are supported and preserved. After this change, symlink files were correctly identified and backed up.
What You Can Do
Confirm if your NAS share uses Amazon FSx for Windows over SMB.
If symlink backup is required, consider switching to NFS.
Review AWS DataSync documentation to understand symlink handling limitations over SMB .
Set up your Druva backup to use the NFS protocol for FSx shares whenever symlinks are present.